These Top 100 lists are updated every month by the United States Chess Federation. As of the June 2014 list, ages will be as of the first day of the month in which those ratings become official. For example, ages for the December lists will be as of December 1. (For Top 100 lists before June 2014, ages are as of the first day of the previous month.)
Ratings shown are the official US Chess ratings for the month indicated, which are generated on the third Wednesday of the month before they become official. The list shows only current US Chess members with established ratings and rating activity in the last year.

About the Arizona Chess Federation, Inc. (ACFI) arizonachess.org:

The Arizona Chess Federation, Inc., the state affiliate of the United States Chess Federation. The ACFI, as the state chapter of the USCF, directly sponsors and arranges for an annual US Chess rated State Championship. The ACFI also directly sponsors and holds the annual US Chess rated Arizona Scholastic State High School, Junior High, Middle School and Elementary School Championships. It also arranges for other chess tournaments throughout the State and be involved in tournament coordination within the State and with the US Chess Tournament Clearinghouse Representative. The Arizona State Chapter supports chess throughout the state and exhibits geographical representation in its tournament sponsorship. Examples include statewide and geographically rotating; Rated Beginner Open tournaments, Swiss Format, tornados, quads as well as: participation in National Chess Day Activities, Regional and National Championships.

About the United States Chess Federation (USCF) uschess.org:

The USCF is a 501(c)(3) nonprofit organization dedicated to empowering people through chess one move at a time. The USCF serves as the organizing body for chess in the United States for over 80,000 members.
The United States Chess Federation (USCF or US Chess) is the governing body for chess competition in the United States and represents the U.S. in FIDE, the World Chess Federation. USCF administers the official national rating system, awards national titles, sanctions over twenty national championships annually, and publishes two magazines: Chess Life and Chess Life for Kids. USCF was founded and incorporated in Illinois in 1939, from the merger of two older chess organizations. It is a 501(c)(3) non-profit organization headquartered in Crossville, Tennessee. Its membership as of 2016 is over 85,000.

USCF organizes or sanctions various national championships. The US Chess Federation holds these annually. The oldest USCF tournament is the U.S. Open. Three Invitational scholastic events are held concurrently: The Denker Tournament of High School Champions, the Dewain Barber Tournament of K-8 Champions, and the National Girls Tournament of Champions. Players qualify for these events by winning state scholastic championship tournaments.